Photography



May 15, 1928. Y 1,669,506

H. C. J.` DEEKS PHOTOGRAPHY Filed OCL. l, 1924 l @fg Ce//u/o/zlSaba/femm fw MU@ Svwefnto z Patented May 15, 192s.

HIBAM C. J. DEEKS, F SEA GLIFF, NEW YORK.

PHOTOGRAPHY.

Application led October 1, 1924. Serial No. 741,060. l

Prior to making the present invention, I had employed the color pigmentsdescribed and patented in my Letters Patent No. 1,430,061 dated,September 26, 1922 to produce colored gelatin reliefs fromcolor-separation negatives, the gelatinreliefs then being combined, i.e., superposed in register, to produce a photograph in natural colors.

The present invention is the outgrowth of my efforts to simplify theprocess by which that result was reached.

The combining and sticking together of three monochromes to produce aphotograph in natural colors has never beenl a sim le 16 operation. Inmy 'former process, to which I have just referred, the gelatin reliefs(produced with a bichromate sensitizer) were very delicate while wet andfor that reason had to be thoroughly dry before any attempt 20 could bemade to combine them. That meant considerable delay before any -finalresult could be reached; and moreover, since the registration of thegelatin reliefs could only be effected after they were dry, specialapparatus had to be provided to permit the gelatin reliefs to beseparated after registration for the application of moisture forsticking. nd then be brought together again and seale in exactregistration. In addition to gothese requirements, a long exposure witha high-powered arc lamp `was required to print upon the bichromatedgelatin which substantially added to the cost. And finally, ,thebichromated gelatin tissue itself would not keep for any length of timebut re uired almost immediate use. All of these (things taken togethermultiplied the cost and difiiculties of the process` necessitated a longand careful combining operation before any picture could be seen, andthus greatly limited the availability of the process for both ama teurand'commercial use.

In my efforts to simplify that process, I have discovered that byembodying my pigments in a silver-gelatin emulsion and exposing andtreating the same in the manner hereinafter described, I can producecolored gelatin reliefs so tough as to be easily reg- `isterablc, oneupon another, while still Wet; and this enables me to do away 'entirelywith any apparatus for registration and combining the three monochromesand also reduces very substantially the time'required to produceandfinish a photograph in natural colors since it is no'longer necessary towait for each of the monochromes to dry before combining them together.y

I have also` discovered that any wet elatin relief prepared, ashereinafter descrlbed, from my colored silver-gelatin film mounted on avery thin celluloid backing, appears` to thoroughly dry out althoughheld tightl compressed between two layers of Celluloid; one layer beingthe original backin upon which said relief was made and the ot er thebacking of an adjacent relief with which the first is combined inregister;' and4 also that when so combined perfect optical contact maybe obtainedbetween the reliefs to produce true color blending. y Itresults, therefore, that no transfer of the color films from one backingto another is required, but the reliefs may retain their originalbacking throughout wit-hout producing any defects either in the opticalproperties of the finished picture or in the drying of the reliefswhich, when dry, remain t to ether.

nstead of employing a yellow colored pigment made in accordance with myaforesaid invention, for the yellow relief, in my present improvedprocess I found it desirable to use chrome-yellow inasmuch as this isfaster to light than any known yellow dye capable of employment inmanufacturing my o wn color pigments; and I discoveredthat with thischrome-yellow the radations of the yellow relief more accurate yrepresented the gradations of thel negative than. in the' case of the*red and blue reliefs. That led to the discovery that` by incorporatingchromeyellow in both the red and blue reliefs, in addition to the normalamounts of my 'red and blue colored pigments respectively, I was able toproduce much more accurately the gradations of the red and blue printingnegatives than had been possible wit out the admixturc of thechrome-yellow; and, in

addition, I discovered -that the clearing bath 'employed for clearingthe relief after developing and bleaching, as described hereinafter,would also, if the reliefs were allowed to remain therein long enough,dissolve out the chrome-yellow in the end. In

ser

oroughly and permanently'united this way, I found that I was able toreproduce. accurately in all three gelatin reliefs the gradations of thenegative without adding any additional step to the process as a whole.

From the foregoing it will be understood that the simplifications of myformer process have been brought about through the embodiment of mycolor pigments in a silvergelatin film;l and I will now describe howthis film is produced and used. I may say here that my improved film maybe developed in a manner similar to that of a bromide print and thentreatedto harden the gelatin where the silver has been blackened, withthe result that the unhardened gelatin may be washed away andtheblackened silver bleached out so as to leave a pigmented gelatinpositive in relief.

In manufacturing the film a silver-bromide emulsion is prepared in thecustomary manner but having as large a proportion of silver-bromidetherein as will not incur liability of precipitation and, preferably,the proportions are such that the emulsion will contain about l1 percentum of gelatin. This proportion of gelatin is somewhat higher thanusually used in coatingcelluloid film; but the celluloid which I preferto use is much thinner than that ordinarily used for similar productsand I have found it advisable to have a more viscous emulsion so thatthe coating will lie more evenly and without streaks on a veryV thinbacking of celluloid.

Ordinarily, a gelatin-silver emulsion is permitted to stand severalhourswhile being maintained at a high temperature, this process or stepinthe making of the emulsion being termed, digesting The digestingprocess adds to the speed or sensitiveness of the emulsion, but it alsorenders it somewhat unstable and lowers its keeping qualities, and thisis especially so if my color pigments are incorporated therein.Moreover, a fast emulsion is less desirable for my purpose for manyvreasons, although of course it is possible to obtain fair results evenwith a fast emulsion. Preferably, therefore, I dispense ,with digestingthe emulsion so that when it is mixed and ready I immediately add mycolors.

For this purpose I take 130 c. c. of a twelve per cent gelatin solutionand place fthe same in a two gallon ball-mill. I then turn the mill overa few times so that the balls are covered with the gelatin solution andthen add 53 grams of my transparent blue pigment and 27 gramsof'chrome-yellow. For a more particular description of my transparentpigments I refer to my Letters Patent aforesaid where a completedescription thereof is given, it being sufficient to note vvhere thatsaid color pigments are produced by spraying a dyed solution of a resin,such as sandarac, in alcohol and collecting the fine impalpable powderwhich results. T hemill is then closed and allowed to grind for twentyminutes, after which 4000 c. e. of the silver emulsion previouslyprepared and kept in liquid form by continuing the temperature at 94oF., is added and the mill again 'allowed to revolve for ten minutesmore. The ,coloring matter has now become thoroughly mixed with theemulsion and the mixture iis poured from the mill, filtered throughcloth, and poured into the pan o f the coating machine.:

The red and yellow colors are ground and mixed with the same amount ofemulsion as for the blue color but I take 47 grams of my transparent redand 33 grams of chromeyellow for the red color and 50 grams ofchrome-yellow for the yellow, color, the chrome-yellow being the onlypigment used for the yellow.

In the accompanying drawings I have illustrated by views of exaggerateddimensions, thc structure of color sheets prepared in accordance with myinvention and also a. three color photograph produced; from said sheets.In said drawings Figure l illus-l trates thc several sections of my bluesheet; Figure the several sections of mv red sheet; F1gure3 the severalsections of my yellow sheet; and Figure 4 the several sections of acomplete photograph formed from the several sheets upon a paper backlaid upon a glass plate.

vBefore applying the coatings of color .the

celluloid should preferably be coated with i, a substratum on bothsides,--the usual prati" tice adopted in similar coating operations inorder to make the emulsion adhere sufficiently to the celluloid. Such asub-stratum may be the usual mixture of gelatin dissolved in acetic acidandfthen mixed with alcohol. The blue coating is applied to thecelluloid having only the sub-stratum as deserlbed above; but thecelluloid which is to be coated with the red emulsion and the celluloidwhich is to be coated with the yellow emulsion I first back with what Icall a sticking coat so that when the yellow and red films are laid thecelluloid in each case 1s coated on one side with the pigmented emulsionand on the other side with this sticking coat. The mixture for thelatter is as follows:

Water 7000 cc. Grelatxm.T 490 grams Acetxc acid 90 ce. 3% chrome-alumsolutionu-" 560 ce.

- liefs as hot water bath which is used as part of y `the treatment inmaking the positive reliefs or monochromes presently to be described.When vthe sticking coat is dry the red or yellow emulsion is coated onthe other side 1n the usual manner.

I have already said that I prefer to use they thinnest Celluloidprocurable; and at the time of the application for this patent I lindthat Celluloid of n003 inches thick to be satisfactory. One reason whythe Celluloid should be as thin as possible is to permit the wetreliefs' to dry while they are held tightly Compressed betweeny twolayers of Celluloid as is the case when the combining of the threemonochromes has been completed. I have found that this drying appears totake place through the Celluloid and that at the end of abouttwenty-four `hours after combining, the reliefs seem to be thoroughlydry and firmly adhered together. Another reason for employing very thinCelluloid is to maintain the three gelatin're` closely together'y aspossible and thus avoid any parallax effect; moreover, on account'ot thesomewhat yellowish color of the Celluloid, it is desirable that it bevery thinin order to interfere as little as possible with the clearrendition of the whites of the picture.

The incorporation of chrome-yellow, I have found, helps to produce theCorrect relief gradations in the gelatin, that is, to make themcorrespond to the tone values of the negative and hence enables me toproduce exact duplieations of colored prints. Besides this, theincorporation of chromeyellow enhances the keeping qualities and titirender the prevents fogging in that its opaque nature interferes withthe penetration into the film of any dangerous light during theoperations of manufacture and use; for a salticient duration of exposureof any light-sensitive silver-emulsion to any so-called safe rcdor greenlight will cause it to become light struck and while such fogging is tobe avoided in ordinary black and white photography, it is much moreobjectionable in color work because all fogging is represented in thefinished picture by an entirely visible color pigment deposit.

Moreover, the use of chrome-yellow also helps to control thesensitiveness of the emulsion. rll`he addition of a larger amount ofchrome-yellow to the red emulsion than to the blue, physically decreasesthe effect of the extra sensitiveness chemically produced by the redpigment and further'decreases it so as to compensate Jfor the-desensitizing effect chemically produced by the blue pigment.' The.proportion of chromeycllow in the red and blue mixtures together withthe roportions of red and blue plgment use may thus be so adjusted as totwo mixtures of somewhat near equal sensitiveness to each other and tothe yellow mixture wherein chrome-yellow is used as the sole colorpigment and has no chemical effect either'to increase or decrease thesensitiveness of the emulsion. It will be understood, of course, andwill be explained later on, that all of the chrome-yellow in the red andblue reliefs is dissolved out and, unlike the case of the yellow relief,forms no part of the color pigment in those reliefs when the are readyto be combined. It may be possi le, therefore, to use, in 'the case ofthe red and blue pigments, some other opaque dissolvable matter to keeunder control the penetration of the-light action and so produce therelief gradations (and therefore the tone values) in accordance withthose of the ne ative.v

From a. practical stan point, it is uite important to have'the blue, redand ye low emulsions all of the same, or as nearly the same,sensitiveness as possible so that with a set of three-color separationnegatives of equal density the same exposure may be given to eachbecause, if the operator in making the three exposures has to take intoConsideration three printing sheets having a differentsensitiveness-ratio in addition to three negatives having anotherdilerent ratio or density the difiiculty of procuring accurately exposedand balanced Color prints becomes obvious.

For the same reason, it is important that the emulsion shall not be toofast as I have already stated; for the faster the emulsion, the lessdependable the results. It is far more important that my improvedpigmented emulsion should have plenty of latitude in exposure, notendency to 4fog if developed athigher than normal temperatures and havegood keeping qualities Vthan that the emulsion be fast; and bymanufacturing the lilm as described above, I have found that anabsolutely dependable roduct may be obtained with a substantial)latitude of exposure, development and other required treatment.

I have found that the incorporation of chrome-yellow in a silver-gelatinemulsion gives the emulsion a wonderful latitude of exposure. It seemsalmost impossible to ovcrexpose such a lm while no additional step isintroduced to the process of making a negative since the chrome-yellowis dissolved out at the same time as ver in the ordinary h po fixingbath.

lliith respect to tlie stickmg coat described above, I have found thatwithout this insoluble gelatin coat there appeared to be, in the lighterportions of the combined and finished print where very little pigmentedgelatin remained, an interfering reflection of light which prevented theproper viewing of the combined colors in those portions. This did notseem to be caused by a layer of the unblackened sil' celluloid,producing a enabling the reliefs Ato be stuck together conmade throughthe Celluloid `surface of theV emulsion.

yeniently,'but.as. producing perfect optical contact when so united.Moreover, I point out that this result would notbe practicable solublecolors were used, that is to say, if the reliefs were dyed and thenplaced 1n contact with the wet sticking coat; for the dyes wouldimmediately run out of the gelatin into the sticking coat the momentregistration. was attempted, and the entire sticking coat would becomepermeated with dye and the dye would be withdrawn from the parts of thepicture where required to produce the proper effect. But with my specialtransparent though insoluble pigments, to Which I have referred and inwhich the dye is retained by the resin and hence. cannot be absorbed ordrawn out of the reliefs by water ,or moist gelatin,l the sticking coathas noeffect Whatever upon the color and the result sought is perfectlypracticable.

Now, a brief explanation of the use of my improved color films will begiven. It will be understood, of course, that in printing upon thesefilms from three-color separation lnegatives,.the negative taken throughthe green filter is printed onto the red film, the negative through thered filter onto the blue film and the negative through the violet filteronto the yellow film. For contact printing, the negative is firstputinto the printingframe with the emulsion side inwards as in ordinaryprinting. The film containing my improved emulsion is thon -insertedwith the shiny or Celluloid surface next to the negative because theexposure is and not on the For projection printing, a printing frame isstill used but ilain glass 1s put in place of the negative.

he three negatives are successively exposed on their corresponding filmsand then developed, the exact exposure times being determined accordingto the.density of the negatives but easily determined after a littlepractice.

The three prints are then preferably developed together for the samelength of time, care' being taken that they are not exposedany longer todarkroom light than is absolutely necessary. After development they -arerinsed and then immersed for ten minutes in a fixing solution.. Thethree prints are now washed in running water for at least fifteenminutes; and itis Very important that this washing be thorough and thatthe emulsion side be no touched during -plate is that time. Afterwashing, the printsare transferred to a bleach-hardening bath` whichcauses the black image to disappear 1n of blackened silver of the imageand, atthe same time, the blackened silver is bleached or changed intowliitish silver salt.

Next, the three prints are transferred directly to a warm water bath ofabout 100 F., until the soluble gelatindissxilves away, during whichtime the film surface should not be touched. This treatment requiresfrom fifteen to twenty minutes and when complete the positive colorclearly visible. After the warm water washing the red and blue reliefsare immersed in a clearing solution for fifteen minutesor until theyellowish and greenish tint has disappeared from the shiadows. Thisclearing solution removes the remaining silver and also thechrome-yellow. Thel yellow relief must not be put in the clearingsolution but instead should be immersed for two minutes only in a fixingsolutionthe same as was usedjdirectly after the developing operation.

The three reliefs are now immersed in cold, running water for about fiveminutes and then are ready to be combined in regis- 'ter while still wetupon white paper in the Take a sheet of glass following manner: aboutone inch longer .andwider than the size of the film and a piece of whitepaper cut the same size as the color-sheet. The

image will appear in los papershould be thin and have a smooth suriface. The paper is placed next to the glass plate and both are heldtogether under Watcr for about fiveseconds to allow the paper to becomethoroughly soaked. They are then taken together" from the Water andallowed to drainl for a few seconds keeping the paper in the lcenter ofthe plate. The plate with the paper upon it is now placed again underwater and at the same time the yellow positive relief is brought intoposition under Water on the paper, thc color side being next to thepaper. The plate with the paper and yellow positive together are nowslowly withdrawn from the water in such manner that no air bubbles areretained between, and the surplus water is squeegeed out.- The glassplate with the yellow relief thereon is again placed in the Water andthe red relief is brought into contact with the color side next to theyellow one and the then withdrawn from the Water as red relief can nowbeslid into before. The

perfect register with the yellow relief by i holding the'glass platewith the fingers and using the thumbs at opposite edges of the redrelief. All of the reliefs are quite tough and hence, though wet, theyare not affected in the least by this treatment. When regisllo lill)neeaooe tration has been effected the surplus Water is squeegeed out asbefore, care being taken not to disturb the register by squeegeeing;but, if the register has been disarranged it can be corrected by furthersliding of the red relief. The same procedure is repeated for the bluerelief.

T he complete image is visible at once in natural colors at this point;but before the complete print is iinished it must be allowed to dry,drying causing the three elements of the picture to thoroughly andpermanently adhere together'. For this it is preferable to seal theedges of the print upon the glass with guinlned paper tape. Thisprevents curling up and separating during drying. Drying requires abouttwenty/fouihours Without any change taking place in the pieture, afterwhich the print is removed from the glass by (-uiting through the tapealong' 'the edges of the print with a sharp penknife.

l have found it particularly desirable to use the following' solutionsto obtain the best results and hence I append `them hereto.

For the developer.

Tank

- Tray rlhe above solutions will keep well in stoppered bottles. For usemix together equal quantities oit A and B.

For the cvz'ng solution.

Tray Tank Hypo- 3 oz. or 85 g 1% lbs. Water... V16 oz. or 450 c. c 1gal.

A hypo bath containing acid, alum, or other ingredients should not beused.

For?` the bleach-hardening bath.

Tray Tenir Copper sulphate (C. R). 11% oz. or 37 g 10b/2 oz. Potassiumbromide 11% oz. or 37 g 10%; oz. Ammonium bichromate. 143 grains or 9.25g 2% oz. Acetic acid (g1eeis1)- 210 minims or 12.5 c. c 3% oz. Water 16oz. or 450 c. c 1 gal.

Tray Tank 4 oz. or 113.6 g 1% lbs. 16 oz. or 450 e. c 3 qta.

When dissolved add the following (rst thoroughly dissolving it).

Tray Tank Potassium meta-bisulphite os. or 10.5 g 2% oz. Powderedehromeeum.-. M oz. or 7 g-.." 1% oz. Water 4 oz. or 1x5 c. c 24 oz.

l claim as my invention:

1. A. silver-halide-sensitive emulsion containing transparent colorpigments and chrome yellow distributed uniformly throughout theemulsion.

2. A silver-halide-gelatin emulsion oontaining chrome-yellow distributeduniformly throughout the emulsion.

3. A photographie ilm comprising a transparent backing, a sensitivecoating on one side containing tine transparent colorpigmentsrinsoluble-in Water and a sticking coat on the other.

In testimony whereof, li have signed my name to this specification' this30th day ot September, 1924.

HRAM C. J. DEEKS.

